[d]r1bq1rk1/1p3ppp/p1nbpn2/2pp4/3P4/2PBPNB1/PP1N1PPP/R2QK2R w KQ - 5 9
Stockfish 7, default settings (1 thread, 1pv, 16MB hash etc.; no real change if hash upped to 512MB), Win64 in Arena GUI:
Code: Select all
1/1 00:00 84 42,000 +0.11 9.0-0
2/2 00:00 147 73,500 +0.28 9.0-0 Bxg3
3/3 00:00 268 134,000 +0.31 9.dxc5 Bxc5 10.0-0
4/4 00:00 362 120,666 +0.81 9.dxc5 Bxg3 10.hxg3 a5
5/5 00:00 797 265,666 +0.43 9.Bxd6 Qxd6 10.dxc5 Qxc5 11.0-0
6/6 00:00 2,079 519,750 +0.22 9.0-0 Bxg3 10.hxg3 b6 11.Bc2 c4
7/8 00:00 3,664 732,800 +4.12 9.Bxd6 cxd4 10.Bxf8 dxe3 11.fxe3 Qxf8 12.0-0
8/9 00:00 5,863 837,571 +0.59 9.Bxd6 Qxd6 10.dxc5 Qd7 11.Nb3 Qe7 12.0-0 e5
9/13 00:00 17,411 916,368 +0.27 9.dxc5 Bxc5 10.0-0 Qe7 11.Ne5 Bb6 12.Nxc6 bxc6 13.e4
...
Stockfish 6, same settings
Code: Select all
1/1 00:00 86 86,000 +0.27 9.0-0
2/2 00:00 150 150,000 +0.42 9.0-0 Bxg3 10.hxg3 cxd4 11.exd4
3/3 00:00 272 272,000 +0.40 9.Bxd6 Qxd6 10.0-0
4/4 00:00 473 473,000 +0.44 9.dxc5 Bxc5 10.0-0 b6
5/5 00:00 762 762,000 +0.55 9.dxc5 Bxg3 10.hxg3 b6 11.cxb6
6/6 00:00 1,053 1,053,000 +0.55 9.dxc5 Bxg3 10.hxg3 b6 11.cxb6 Qxb6
7/8 00:00 3,670 3,670,000 +4.22 9.Bxd6 cxd4 10.Bxf8 dxc3 11.bxc3 Qxf8 12.0-0
8/9 00:00 6,273 6,273,000 +4.29 9.Bxd6 Nxd4 10.Bxc5 Nxf3+ 11.Nxf3 Re8 12.0-0 b6 13.Ba3
9/11 00:00 12,332 12,332,000 +0.50 9.Bxd6 Qxd6 10.dxc5 Qe7 11.0-0 e5 12.e4 Bg4 13.exd5 Nxd5
...
+4.22 9.Bxd6 cxd4 10.Bxf8 dxc3 11.bxc3 Qxf8 12.0-0
+4.29 9.Bxd6 Nxd4 10.Bxc5 Nxf3+ 11.Nxf3 Re8 12.0-0 b6 13.Ba3
Depth 8 strikes me as rather late to be blipping on an obvious recapture, one that was evaluated correctly at depth 5 (SF7) or 3 (SF6). The issue is absent in Stockfish 5 and all earlier versions I've tried, and absent in Komodo 9.3.
I will soon make a post on the computer science blog Gödel's Lost Letter (https://rjlipton.wordpress.com/) about a matter of larger interest. The relevance of low-depth values for predicting human actions is shown in the post https://rjlipton.wordpress.com/2015/10/ ... tisficing/ last October. I'm also simply curious---I don't think it's a hash-collision issue and (as the post will show) it shows up frequently at depths up through 8 but is better at 9 and evidently mostly gone by depth 10.
(I've posted this here rather than in the technical forum because it's not referring to code or algorithm strategy directly, though moving it there would be OK with me.)